城市供水系统摇蚊污染发生与防治研究

近年来 ,国内已有 1 0余个省区城市供水系统中先后发生了摇蚊幼虫 (红虫 )污染事件。文章介绍了国内外供水系统摇蚊发生概况 ;分析了供水系统中摇蚊发生的 3个主要原因 :原水环境污染 ,水处理过程摇蚊污染和二次供水污染。简要回顾了国外供水系统摇蚊污染防除的历史和进展 ;重点介绍了目前国内供水行业所采用物理、化学以及生物的方法在水厂净水处理及二次供水过程防除摇蚊污染的研究 ;同时指出了当前有关研究和实践中存在的主要问题是对摇蚊生物学和生态学等知识的缺乏。对该问题开展进一步研究提出了建议     

Bacterial population dynamics and community structure in a pharmaceutical manufacturing water supply system determined by real-time PCR and PCR-denaturing gradient gel electrophoresis

AIMS: To control bacteria in the pharmaceutical water supply system. METHODS AND RESULTS: Bacteria were enumerated by conventional culture method and fluorescent vital staining. Activated carbon treatment and storage in a tank provided favourable environments for bacterial growth. The bacterial population of the water in both the post-activated carbon treatment and the tank was analysed by denaturing gradient gel electrophoresis (DGGE) with PCR-amplified 16S rDNA fragments including V6, -7, and -8 regions. The bacterial community structure in activated carbon treated water was stable throughout the year. Several kinds of bacteria such as genus Aquaspirillum and Methylobacterium were found in the water after activated carbon treatment. The bacterial community structure was changed and other bacteria such as mycobacteria were detected after storage. Mycobacteria were quantified in water samples using real-time PCR targeting the 16S rDNA gene. Mycobacteria were also detected in tap water and their number was increased 10(3)-10(4)-fold higher after storage. CONCLUSION: These data suggest the importance of culture-independent methods for quality control of water used in pharmaceutical manufacturing. SIGNIFICANCE AND IMPACT OF THE STUDY: Critical steps and specified bacteria that should be controlled in the water supply system were recognized by culture-independent methods. These data will enable effective control of water used in the pharmaceutical industry.     

The role of bacteria in pH increase of nettle water

The investigation was designed to elucidate and explain the pH increase observed when a water extract of stinging nettle,Urtica dioica, was supplied to plants grown in sand or peat culture. The pH, bacterial number, organic acid content, and NH ₄ ⁺ and NO ₃ ^– content were determined in aerated nettle water, sterilised (UV-treated) nettle water and nutrient solution at intervals during 48 h. The pH increase was closely linked to increase in aerobic bacteria and the simultaneous decrease in organic acids and NH ₄ ⁺ concentration in the media. Consequently, the pH rise in nettle water is due to consumption of organic acids by bacteria and the accompanying shift of the acid-base equilibrium towards a more basic state.     

Microbiological quality of water and dialysate in a haemodialysis unit in Ponta Grossa-PR, Brazil

AIMS: The objective of the study was to determine the microbiological quality of samples of water and dialysate in a haemodialysis unit. METHODS AND RESULTS: Seventy-two samples each of water and dialysate were collected during November 2003 to April 2004. The following microbiological analyses were performed: test for total and faecal coliforms, which produced negative results for all the samples; counts of total heterotrophic bacteria, where three samples of water and two of dialysate showed levels higher than those permitted by national standards; and endotoxin assay, which revealed high quantities only in samples of water that preceded reverse osmosis. Nonfermenting Gram-negative bacteria were identified in 54 samples of dialysate and in 26 samples of water. The test for adhesion to an inert surface showed that various bacteria were capable of forming biofilms. Twenty-seven per cent of the bacteria were resistant to sodium hypochlorite at 500 ppm for 10-min contact time. Sixty per cent of the isolates were resistant to three or more antibiotics. CONCLUSIONS: Water and dialysate can be a source of infection for patients who need haemodialysis. SIGNIFICANCE AND IMPACT OF THE STUDY: An adequate system for water treatment, disinfection of the haemodialysis system and microbiological monitoring of the water and dialysate are necessary to reduce bacteraemia and pyrogenia outbreaks.     

革兰氏阴性菌脂多糖运输系统的构成及作用机制

革兰氏阴性菌包含有两层组分不同的膜结构——内膜和外膜,对大多数革兰氏阴性菌而言,脂多糖(lipopolysaccharides,LPS)是其外膜上最主要的脂质成分,锚定在外膜小叶(the outer leaflet of the OM)上,是革兰氏阴性菌固有免疫的重要组成部分。脂多糖运输系统(lipopolysaccharide transport system,Lpt)将胞内装配完整的LPS正确装配到外膜,使得与脂多糖相关的阻渗、有机溶剂耐受性、疏水性抗生素耐受性、膜通透性等功能得以实现。该运输系统的正确作用主要依赖7个不同的脂多糖运输蛋白(Lpt ABCDEFG)协同完成,整个系统贯穿细菌内膜至外膜,由内膜上ABC转运体复合物Lpt B2FG、胞质内转运协同蛋白Lpt A/C及被许多学者称作脂多糖运输的"命门"的外膜蛋白复合物Lpt DE共同构成。本文就革兰氏阴性菌脂多糖的具体结构功能进行简介,进而综述脂多糖运输系统的7个蛋白的构成和作用机制,以期为进一步研究该系统中每个蛋白的功能提供理论基础及参考。     

五倍子对池水细菌和藻类的影响

在试验水族箱内,研究不同浓度的五倍子药液对池水中细菌和藻类的影响.结果表明:用药72h时,细菌总数的减少与药液浓度呈显著相关(r=-0.84349,P<0.05);浓度高于3mg.L-1处理时,细菌总数平均下降了96.2%,其中革兰氏阴性细菌的菌群比例下降达最大值;超过72h,细菌总数呈上升趋势.一定浓度的五倍子药液对池水藻类具有短时间的抑制作用.用五倍子药液对养鱼池塘消毒防病,浓度以3mg.L-1,消毒时间以72h为宜.     

细菌Cpx双组分信号转导系统应对外界环境变化的响应调节机制研究进展

细菌能够在其他微生物无法生存的环境中生长,必然具有更加强大的适应外界环境的能力.细胞信号转导的效率决定了细菌对外界刺激做出应答反应的速率和能力.双组分调控系统是维持细菌在压力环境中存活的重要结构.Cpx双组分信号转导系统是革兰氏阴性菌中普遍存在的双组分调控系统之一,在响应外界环境变化并做出适应性反应的过程中起着主要作用...     

Further studies on the distribution of cytochromes in methanogenic bacteria

Abstract Growth of Methanobacterium thermoautotrophicum strain Marburg was strongly inhibited by 2 μg/ml of pseudomonic acid. This inhibition was relieved by 10 mM l -isoleucine. The susceptibility of a pseudomonic acid-resistant mutant was 50 times lower than in the wild type. Isoleucyl-tRNA synthetase activity in cell extracts from the wild type was strongly inhibited by pseudomonic acid whereas the corresponding enzyme in mutant extracts was only marginally inhibited by the antibiotic.     

铁还原菌在水资源再生与能源转化领域的研究进展

铁还原菌是一种典型的异化金属还原菌,广泛分布于海洋沉积物、陆地深地层等自然环境,该类细菌可以将铁氧化物中的Fe(Ⅲ)还原为Fe(Ⅱ),在铁、碳的生物地球化学铁循环中发挥重要作用。铁还原菌的末端电子不局限于Fe(Ⅲ),还可以是其他高价金属、有机污染物,可用于土壤、地下水的污染修复和毒性削减。在微生物电化学系统中,铁还原菌氧化有机物产生的电子直接传递给电极,可以产生电能。基于这种独特的胞外电子传递方式,衍生出了微生物燃料电池、微生物电解池、微生物脱盐电池、微生物燃料电池耦合芬顿反应以及光催化微生物燃料电池,常用于微生物发电、生物传感器、生物制氢、定向发酵、海水淡化、生物脱盐和污染物分解矿化。本文从异化铁还原菌的代谢机制、微生态作用、环境修复、水资源再生与能源转化四个方面,综述了铁还原菌的作用原理及国内外研究现状,分析论述了目前亟需解决的关键问题和未来的研究方向,以期为铁还原菌的基础理论研究和应用技术研发提供参考。     

一株紫色非硫光合细菌净化养殖水体初步研究

选取从杭州养鱼塘水样中分离得到的1株紫色非硫光合细菌菌株HZ-1,利用它的纯培养物处理养殖水体,测定COD去除率和亚硝态氮降解率。结果表明,菌株HZ-1可以有效地分解水体中的污染物,去除水体中的COD,对养鱼塘水去除率达到20.99%;对养虾池水去除率达到了36.09%;菌株HZ-1可以有效地降低水体的亚硝态氮,对养鱼塘水亚硝态氮的降解率为41.18%,具有较好净化效果。     

Intestinal bacteria and ageing

Advancements in science and medicine, as well as improved living standards, have led to a steady increase in life expectancy, and subsequently a rise in the elderly population. The intestinal microbiota is important for maintenance of host health, providing energy, nutrients and protection against invading organisms. Although the colonic microbiota is relatively stable throughout adult life, age-related changes in the gastrointestinal (GI) tract, as well as changes in diet and host immune system reactivity, inevitably affect population composition. Recent studies indicate shifts in the composition of the intestinal microbiota, which may lead to detrimental effects for the elderly host. Increased numbers of facultative anaerobes, in conjunction with a decrease in beneficial organisms such as the anaerobic lactobacilli and bifidobacteria, amongst other anaerobes, have been reported. These changes, along with a general reduction in species diversity in most bacterial groups, and changes to diet and digestive physiology such as intestinal transit time, may result in increased putrefaction in the colon and a greater susceptibility to disease. Therapeutic strategies to counteract these changes have been suggested in ageing people. These include dietary supplements containing prebiotics, probiotics and a combination of both of these, synbiotics. Limited feeding trials show promising results with these supplements, although further longer-term investigations are required to substantiate their use in elderly healthcare fields.     

小麦土霉素抗性内生细菌分离、鉴定及分布

研究通过培养的方法研究了小麦根际土壤、根、茎、叶各部位的土霉素抗性内生菌数量、种类和分布特征.结果表明,小麦内生菌数目在1×104cfu g-1～1.95×106 cfu g-1 之间,土霉素抗性内生菌数目介于6.9×103cfu g-1和5.67×105 cfu g-1,从中分离出22株土霉素抗性内生菌,包括15株G+和7株G-,经16s rRNA基因序列分析,它们与Bacillaceae,Alphaproteobacteria 和Gammaproteobacteria 三大类微生物聚在一起,其中Bacillaceae类细菌最多,占59.1%.土霉素抗性的Bacillus licheniformis在小麦根际土壤、根、茎等器官中都分离得到表明该抗性菌种在小麦内生系统中具有较高的传播性;具有土霉素抗性的人类机会致病菌Bacillus cereus和Stenotrophomonas属的细菌在小麦的根际土壤、根以及叶子中也均分离到,但是在小麦种子中没有分离到任何土霉素抗性的内生菌.     

高效净水细菌的分离鉴定及其净水能力分析

[目的]分离筛选获得能高效净化污水的净化细菌。[方法]利用氨氮降解筛选培养基对某污水处理厂的活性污泥进行净水细菌的分离筛选,并研究分离菌株对污水有机质、氨态氮、总磷与总氮含量的去除效果以及药敏性分析。[结果]比较去除效果,获得了1株最高效的净水细菌,该菌株对污水有机质、氨态氮、总氮与总磷均具有较强的净化效果,其去除率分别达58. 90%、65. 45%、51. 91%和35. 00%。结合菌落形态特征观察、生理生化分析及分子鉴定,鉴定该菌株为暹罗芽胞杆菌(Bacillus siamensis)。该菌株对7种常见抗生素均具有一定敏感性,其中对氨苄青霉素最敏感,卡那霉素次之,对庆大霉素最不敏感。[结论]分离筛选获得1株能高效净化污水的暹罗芽胞杆菌,对常见抗生素具有一定敏感性。     

红掌组培苗继代过程中细菌污染的防治试验

针对红掌组织培养过程中易出现细菌污染的问题,进行多种抗菌素处理及二次升汞灭菌处理对细菌污染的防治比较试验。结果表明,用300mg/L青霉素+180mg/L链霉素溶液注射到培养基表面,能有效控制细菌污染,且对组培苗生长影响最小。     

大熊猫源细菌耐药性研究进展

耐药菌和耐药基因已成为一种新型环境污染物,引发世界公共卫生问题。细菌耐药性尤其是多重耐药菌在人医临床、畜禽养殖以及环境传播等多个方面得到越来越多的关注,而关于大熊猫等野生动物的耐药性研究相对较少。大熊猫(Ailuropoda melanoleuca)是世界公认的珍稀野生动物,其种群数量易受到各种疾病的威胁,尤其是肠道细菌性疾病。随着抗菌药物在疾病预防和控制中的普遍使用,由此带来的耐药性危害日益明显。本文总结了关于大熊猫源细菌耐药的国内外研究报道,对其耐药表型、耐药基因型、耐药机制及水平传播机制等方面内容进行了综述,旨在为大熊猫源细菌耐药性的研究和防控提供依据,为临床科学用药提供理论参考,从而助力大熊猫迁地保护。     

细菌中CRISPR/Cas系统的应用和优化

成簇规律间隔短回文重复序列(Clustered regularly interspaced short palindromic repeats,CRISPR)系统在近年来得到越来越广泛的应用。相比传统的基因组编辑技术,CRISPR/Cas系统具有编辑效率高、特异性强、花费低、对实验技术要求低等优势。其中Ⅱ型和Ⅴ型CRISPR/Cas系统分别仅需要单个Cas9蛋白和单个Cpf1蛋白作为切割双链DNA的工具,因此特别受到研究者们的青睐。目前CRISPR/Cas9技术已成功应用于斑马鱼、小鼠、人类细胞等真核生物的基因组编辑中,并取得一系列重要成果,但在细菌领域进行的相关研究并不多。文中将简单描述CRISPR/Cas系统及其作用机制,重点介绍该系统的优化以及近年来其在细菌学领域所取得的进展。     

Bioremediation of bacteria pollution using the marine sponge Hymeniacidon perlevis in the intensive mariculture water system of turbot Scophthalmus maximus

Sessile filter‐feeding marine sponges (Porifera) have been reported to possess high efficiency in removing bacteria pollution from natural or aquaculture seawater. However, no investigation has been carried out thus far in a true mariculture farm water system. Therefore this study sought to investigate the ability of the marine sponge Hymeniacidon perlevis to bioremediate the bacteria pollution in the intensive aquaculture water system of turbot Scophthalmus maximus. Sponge specimens were hung in fish culture effluent at different temperature to investigate the optimal temperature condition for bacteria removal by H. perlevis. Turbots S. maximus were co‐cultured with sponge H. perlevis in 1.5 m³ of water system at 15–18°C for 6 weeks to control the growth of bacteria. It was found that H. perlevis was able to remove pathogenic bacteria efficiently at 10–20°C, with a maximal removal of 71.4–78.8% of fecal coliform, 73.9–98.7% of pathogenic vibrio, and 75.0–83.7% of total culturable bacteria from fish‐culture effluent at 15°C; H. perlevis continuously showed good bioremediation of bacteria pollution in the S. maximus culture water system, achieving removal of 60.0–90.2% of fecal coliform, 37.6–81.6% of pathogenic vibrio, and 45.1–83.9% of total culturable bacteria. The results demonstrate that H. perlevis is an effective bioremediator of bacteria pollution in the turbot S. maximus culture farm water system. Biotechnol. Bioeng. 2010;105: 59–68. © 2009 Wiley Periodicals, Inc.     

Effect of low-concentration chlorine dioxide gas against bacteria and viruses on a glass surface in wet environments

Aims: To evaluate the efficacy of low‐concentration chlorine dioxide (ClO₂) gas against model microbes in the wet state on a glass surface. Methods and Results: We set up a test room (39 m³) and the ClO₂ gas was produced by a ClO₂ gas generator that continuously releases a constant low‐concentration ClO₂ gas. Influenza A virus (Flu‐A), feline calicivirus (FCV), Staphylococcus aureus and Escherichia coli were chosen as the model microbes. The low‐concentration ClO₂ gas (mean 0·05 ppmv, 0·14 mg m^?3) inactivated Flu‐A and E. coli (>5 log₁₀ reductions) and FCV and S. aureus (>2 log₁₀ reductions) in the wet state on glass dishes within 5 h. Conclusions: The treatment of wet environments in the presence of human activity such as kitchens and bathrooms with the low‐concentration ClO₂ gas would be useful for reducing the risk of infection by bacteria and viruses residing on the environmental hard surfaces without adverse effects. Significance and Impact of the Study: This study demonstrates that the low‐concentration ClO₂ gas (mean 0·05 ppmv) inactivates various kinds of microbes such as Gram‐positive and Gram‐negative bacteria, enveloped and nonenveloped viruses in the wet state.